The National League Championship Series (NLCS), also known as the National League Pennant, is a best-of-seven playoff and one of two League Championship Series comprising the penultimate round of Major League Baseball's (MLB) postseason. It is contested by the winners of the two National League (NL) Division Series. The winner of the NLCS wins the NL pennant and advances to the World Series, MLB's championship series, to play the winner of the American League's (AL) Championship Series. The NLCS began in 1969 as a best-of-five playoff and used this format until 1985, when it changed to a best-of-seven format.

Prior to 1969, the National League champion (the "pennant winner") was determined by the best win–loss record at the end of the regular season. There were four ad hoc three-game playoff series due to ties under this formulation (in 1946, 1951, 1959, and 1962).

A structured postseason series began in 1969, when both the National and American Leagues were reorganized into two divisions each, East and West. The two division winners within each league played each other in a best-of-five series to determine who would advance to the World Series. In 1985, the format changed to best-of-seven.

The NLCS and ALCS, since the expansion to seven games, are always played in a 2–3–2 format: games 1, 2, 6, and 7 are played in the stadium of the team that has home field advantage, and games 3, 4, and 5 are played in the stadium of the team that does not. Home field advantage is given to the team that has the better record, except a division champion would always get home advantage over a Wild Card team. From 1969 to 1993, home field advantage was alternated between divisions each year regardless of regular season record and from 1995 to 1997 home field advantage was predetermined before the season.

In 1981, a one-off division series was held due to a split season caused by a players' strike.

In 1994, the league was restructured into three divisions, with the three division winners and a wild card team advancing to a best-of-five postseason round, the now-permanent National League Division Series (NLDS). The winners of that round advance to the best-of-seven NLCS; however, due to the player's strike later that season, no postseason was played and the new format did not formally begin until 1995. The playoffs were expanded in 2012 to include a second Wild Card team and in 2022 to include a third Wild Card team.

Seven managers have led a team to the NLCS in three consecutive seasons; however, the most consecutive NLCS appearances by one manager is held by Bobby Cox, who led the Atlanta Braves to eight straight from 1991 to 1999. The Braves (1991-1999) are also the only team in the National League to have made more than three consecutive National League Championship Series appearances. Tony La Russa and Jim Leyland are the only managers to lead their teams to three consecutive League Championship Series appearances in both leagues.

The Milwaukee Brewers, an American League team between 1969 and 1997, and the Houston Astros, a National League team between 1962 and 2012, are the only franchises to play in both the ALCS and NLCS. The Astros are the only team to have won both an NLCS (2005) and an ALCS (2017, 2019, 2021, and 2022). The Astros made four NLCS appearances before moving to the AL in 2013. Every current National League franchise has appeared in the NLCS and all teams except the Brewers have won an NL Pennant via the NLCS.

For the first time in history, two wild card teams played in the 2022 National League Championship Series.

The Warren C. Giles Trophy is awarded to the NLCS winner.^[1] Warren Giles served as president of the National League from 1951 to 1969.^[2]

See: League Championship Series Most Valuable Player Award#National League winners

A Most Valuable Player (MVP) award is given to the outstanding player in the NLCS. No MVP award is given for Division Series play.

The MVP award has been given to a player on the losing team twice, in 1986 to Mike Scott of the Houston Astros and in 1987 to Jeffrey Leonard of the San Francisco Giants.

Although the National League began its LCS MVP award in 1977, the American League did not begin its LCS MVP award until 1980.^[3] The winners are listed in several locations:

• in the below NLCS results table, in the "Series MVP" column
• in the article League Championship Series Most Valuable Player Award
• on the MLB website^[4]

• List of National League pennant winners
• List of National League Wild Card winners
• National League Division Series
• American League Championship Series